The ECMNET project

started by Tim Charron, Nicolas Daminelli, Torbjörn Granlund, Paul Leyland, Paul Zimmermann,

continued by you

Note added on July 8, 2016: the web pages provided by my lab no longer allow cgi scripts, which explains why some the links below do no longer work.


The goals of ECMNET

  • Help to find new factors of Cunningham numbers [difficult]
  • Find a record factor [very difficult]

    How can you help?

    1. Download GMP-ECM and compile it on your machine.

    2. Run the program on the Cunningham input list as follows (here under Unix); you'll need about 500MB of memory:

    $ ecm 43000000 < cunningham.in > cunningham.out &

    3. Search for new factors using 'grep found cunningham.out', and report them.

    4. When the program finishes (after one week to one month depending on your machine), download the updated list and restart it.


    Factors found so far [including other ecm implementations] (by date, size, summary).
    Frequently Asked Questions and detailed information on ECMNET

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